From drinking water pipelines and water purification equipment to sanitary systems and household water supply networks, polyketone(PK) is demonstrating considerable potential in water-contact applications.
When we talk about healthy water use, we often focus on water sources, water quality, and filtration technologies, but rarely ask a more fundamental question: are the pipe materials that remain in long-term contact with water equally reliable?
From commonly used shower systems and faucets in daily life, to pipeline systems hidden inside walls, and key flow channel components inside water purifiers, contact between water and materials continuously exists and repeatedly occurs over a timescale measured in years.
In fact, tap water, as domestic water, has already met strict hygiene standards when it leaves the water treatment plant and is suitable for direct drinking. However, during transportation and through household piping systems, tap water may experience secondary contamination that affects water quality. Therefore, before drinking, water is usually boiled for sterilization. This also means that even if the water source is safe, aging, substance release, or microbial growth caused by pipelines or key components during long-term use may still affect actual drinking water safety. Therefore, the stability, safety, and durability of materials themselves have become important challenges that the water-contact industry must continuously address.
Behind Healthy Water Use, What Real Challenges Are Materials Facing?
In domestic water supply systems in China, PVC-C and PP-R are two relatively common pipeline materials. PVC-C improves heat resistance through chlorination modification and can be used for hot water transportation within a certain temperature range compared with conventional PVC. PP-R, with moderate cost and mature installation processes, is widely adopted and has become one of the mainstream choices for residential water supply systems.
However, during long-term service, material structures may face issues under alternating hot and cold water conditions, residual chlorine exposure, and water flow impact pressure environments, including insufficient wear resistance, particle release and scratches caused by impact, and conditions that may promote microbial growth.
In addition, when PP-R pipelines are processed using hot-melt welding technology, the material may form localized protrusions on the inner wall during melting and extrusion, creating flow path restrictions. This can unknowingly increase water flow resistance and the risk of scaling. During long-term contact with tap water, residual chlorine in water may accelerate material aging and potentially lead to pipeline damage.
The problems of traditional iron pipes are more obvious: rust. Iron pipes inevitably corrode in humid environments. Rust not only causes water discoloration and odor but also creates a rough inner surface that becomes a breeding ground for bacteria. When discussing “drinking water,” the water transportation links using these traditional materials may actually become an easily overlooked weak point.
Against this background, polyketone (PK) materials have begun to enter the field of water-contact applications and become an alternative material option.
Polyketone(PK) is a type of engineering plastic synthesized mainly from carbon monoxide, ethylene, and propylene. Its molecular structure is stable and it does not contain harmful substances such as bisphenol A or formaldehyde. Under long-term water contact conditions, it can reduce the risk of small molecule release. This characteristic gives it natural advantages in applications with high hygiene safety requirements, such as shower components, faucet structural parts, and water purifier flow channel components.
What Properties Are Required for Materials in Long-Term Water Contact?
Hydrolysis Resistance and Chemical Resistance：
Water is not a medium with completely identical compositions. Water quality varies significantly between different regions. Changes in residual chlorine, disinfectants, and acidic or alkaline environments continuously test the durability of materials.
Polyketone (PK) demonstrates outstanding chemical resistance performance, with excellent resistance to acids, alkalis, and various oxidizing agents. Its overall chemical resistance is second only to PPS. This means that whether facing high residual chlorine water quality or complex operating environments, the material can maintain relatively stable performance, thereby extending product service life and reducing later maintenance and replacement risks.
Wear Resistance：
In household water supply pipelines, long-term water flow continuously washes the pipe walls, which may cause material wear, inner wall roughening, or particle detachment, affecting water flow efficiency and increasing resistance.
The wear resistance advantages of polyketone (PK) enable pipeline structures to maintain a dense and uniform structure with smooth inner walls. Even under continuous water flow impact, it can maintain stable pipe dimensions, reduce sediment accumulation and blockage risks, while lowering system resistance and ensuring smoother and more efficient water flow.
Barrier Performance：
In addition to visible flow smoothness, there is another easily overlooked factor that has a profound impact on water quality — oxygen barrier performance.
Continuous oxygen penetration in water can accelerate microbial growth and material aging, and may even affect the long-term stability of drinking water systems. In this aspect, differences between materials become particularly significant.
The molecular structure of polyketone materials is highly compact, with short gas permeation pathways. Its barrier performance can reach a level close to EVOH, effectively inhibiting oxygen diffusion through the pipe wall and providing a more stable physical barrier for water. In comparison, traditional PVC pipes have moderate oxygen barrier capability, while commonly used PP-R pipelines have relatively limited inherent oxygen barrier performance and often require additional oxygen barrier layers or multilayer composite structures for improvement.
Heat Resistance and Impact Resistance：
In terms of thermal and mechanical properties, polyketone also demonstrates the “strength” expected from an engineering material. Its Vicat softening temperature can reach 195°C, with long-term temperature resistance of approximately 120°C, allowing it to handle repeated thermal cycling and water pressure fluctuations in hot water systems with ease.
Whether used in pipe joints requiring resistance to instantaneous water pressure impact, or internal faucet and shower components requiring high dimensional stability, polyketone can achieve a good balance between strength, toughness, and stability.
Overall, polyketone PK is demonstrating considerable potential in water-contact applications, ranging from drinking water pipelines and water purification equipment to sanitary systems and household water supply networks.It not only provides new solutions for the limitations of traditional materials in safety and durability, but also offers a stronger material foundation for the industry to establish higher standards between “healthy water use” and “long-term reliability.”
